Steal hearts, say, in smart outfit (7,4)
I believe the answer is:
trouser suit
'smart outfit' is the definition.
'trouser suit' can be an answer for 'outfit' (I have seen 'female outfit' mean 'trouser suit' so perhaps 'outfit' could also mean 'trouser suit'). I'm not certain of the 'smart' bit.
'steal hearts say' is the wordplay.
'steal' becomes 'trouser' (I can't explain this - if you can you should believe this answer much more).
'hearts say' becomes 'suit' (hearts is a playing card suit).
'trouser'+'suit'='TROUSER SUIT'
'in' is the link.
Can you help me to learn more?
(Other definitions for trouser suit that I've seen before include "A matching jacket and pants" , "two-piece attire" , "Two-piece costume" , "Two-piece wear for woman" , "female outfit" .)