In Chapter 1, the narrator sets the scene for the unfortunate developments in Clifford's personality after the war using biting verbal irony. Although Lord Chatterley has been horribly injured, the narrator tells the reader:
His hold on life was marvelous. He didn’t die, and the bits seemed to grow together again.
Typically, if a character were described as having a "marvelous" hold on life, it would imply a positive sort of robustness and resilience. However, the narrator subverts this optimistic idea by pointing out the rather grim reality of the situation. Clifford didn't actually “survive” in the fullest sense, he merely didn't die. His life, post-injury, is flat, cold, and disengaged. The narrator does not say that Clifford’s survival is “marvelous.” They’re implying that his recovery is not actually complete at all, and that it’s actually “marvelous” that he manages to seem plausibly “living.”
The phrase "the bits seemed to grow together again" further amplifies this irony. Instead of describing the heroic recovery of a war hero, the narrator’s tone is bitter and sarcastic. Clifford has not healed: the “bits” of him just look as if they have “grown back together” like dough expanding in a pan. The image Lawrence evokes here is gruesome. It's as if Clifford has been blown to pieces and then stuck haphazardly back together.