Improve husband during atonement, not initially (7)
I believe the answer is:
enhance
'improve' is the definition.
(I know that enhance is a more specific form of the action improve)
'husband during atonement not initially' is the wordplay.
'husband' becomes 'h' (abbreviation).
'during' indicates putting letters inside.
'atonement' becomes 'penance' (I've seen this in another clue).
'not initially' means to remove the first letter.
'penance' with its initial letter removed is 'enance'.
'h' inserted within 'enance' is 'ENHANCE'.
(Other definitions for enhance that I've seen before include "improve things" , "Improve, add to attractiveness of" , "Boost" , "Make even better" , "Improve, make more attractive" .)