Current fixed terms must include answer after separation (4,6)
I believe the answer is:
gulf stream
'current' is the definition.
(Gulf stream is an example)
'fixed terms must include answer after separation' is the wordplay.
'fixed' is an anagram indicator.
'must include' means one lot of letters goes inside another.
'answer' becomes 'a' (abbreviation eg in Q and A).
'after' says to put letters next to each other.
'separation' becomes 'gulf' (I have seen 'Wide separation ' mean 'gulf' so perhaps 'separation' could also mean 'gulf').
'terms' with letters rearranged gives 'strem'.
'strem' enclosing 'a' is 'stream'.
'stream' after 'gulf' is 'GULF STREAM'.
(Other definitions for gulf stream that I've seen before include "thats currently warming us" , "North Atlantic Drift" , "Warm Atlantic current" .)