I initially avoid clubs after what could be ace of hearts (7)
I believe the answer is:
cardiac
'of hearts' is the definition.
(relating to the heart)
'i initially avoid clubs after what' is the wordplay.
'initially' suggests taking the first letters.
'after' says to put letters next to each other.
'what' becomes 'card' (I can't justify this - if you can you should believe this answer much more).
The first letters of 'avoid clubs' is 'ac'.
'i'+'ac'='iac'
'iac' put after 'card' is 'CARDIAC'.
'could be ace' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for cardiac that I've seen before include "Relating to the heart" , "Appertaining to the heart" , "of hearts" , "Relating to 8 down, part one" , "Of the heat, perhaps illness" .)