I'm scared about partner's collapse (4,4)
I believe the answer is:
keel over
'collapse' is the definition.
(I've seen this in another clue)
'i'm scared about partner's' is the wordplay.
'i'm scared' becomes 'eek' (exclamation showing fear).
'about' shows that the letters should be reversed in order.
'partner' becomes 'lover' (romantic partner).
'eek' in reverse letter order is 'kee'.
'kee'+'lover'='KEEL OVER'
(Other definitions for keel over that I've seen before include "Capsize" , "Suddenly collapse" , "Pass out" , "Fall, as in a faint" .)