Affinity in harbour after strike (7)
I believe the answer is:
rapport
'affinity' is the definition.
(rapport is a kind of affinity)
'harbour after strike' is the wordplay.
'harbour' becomes 'port' (I've seen this before).
'after' is a charade indicator (letters next to each other).
'strike' becomes 'rap' (rapping is a kind of striking**).
'port' put after 'rap' is 'RAPPORT'.
'in' acts as a link.
(Other definitions for rapport that I've seen before include "Empathy" , "Feeling of sympathy and understanding" , "Bond of sympathy" , "Close and harmonious relationship" , "Feeling of mutual understanding" .)