Quarrel will ruin end-of-season imports (3-2)
I believe the answer is:
run-in
'quarrel' is the definition.
(I know that quarrel can be written as run-in)
'ruin end-of-season imports' is the wordplay.
'end of' suggests the final letters.
'season' becomes 'ruin' (I can't explain this - if you can you should believe this answer much more).
'imports' means one lot of letters goes inside another (inserted letters are imported).
The last letter of 'ruin' is 'n'.
'n' going into 'ruin' is 'RUN-IN'.
'will' is the link.
Can you help me to learn more?
(Other definitions for run-in that I've seen before include "Disagreement (with authority?)" , "Matches late in season" , "Dispute" , "Home straight" , "Approach" .)