Older relative receiving ring will grumble (5)
I believe the answer is:
groan
'grumble' is the definition.
(I've seen this before)
'older relative receiving ring' is the wordplay.
'older relative' becomes 'gran' (grandmother).
'receiving' means one lot of letters goes inside another.
'ring' becomes 'o' (letter resembling a ring).
'gran' enclosing 'o' is 'GROAN'.
'will' is the link.
(Other definitions for groan that I've seen before include "Sound of one in pain" , "Moan, grumble" , "Sound of pain or despair" , "See 18 Down" , "Sound of pain or disapproval" .)