Struggle making descent (6)
I believe the answer is:
strain
I believe this clue is a double definition.
'struggle' is the first definition.
(I've seen this before)
'descent' is the second definition.
(thesaurus)
'making' is the link.
(Other definitions for strain that I've seen before include "song" , "Weaken -- sieve" , "Difficulty that causes tension" , "'Stress, tension (6)'" , "tax" .)