Make an effort on a tune (6)
I believe the answer is:
This clue is a double definition.
'make an effort' is the first definition.
(I've seen this before)
'tune' is the second definition.
(I know that tune can be written as strain)
'on a' is the link.
(Other definitions for strain that I've seen before include "Filter - intense effort" , "line of ancestry" , "Pour through a sieve" , "Drain off" , "Family - tension" .)