Muscles to hold old lady up for dance (5)
I believe the answer is:
samba
'dance' is the definition.
(sambaing is a kind of dancing)
'muscles to hold old lady up' is the wordplay.
'muscles' becomes 'abs' (I've seen this before).
'to hold' means one lot of letters goes inside another.
'old lady' becomes 'ma'.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'abs' going around 'ma' is 'abmas'.
'abmas' in reverse letter order is 'SAMBA'.
'for' is the link.
(Other definitions for samba that I've seen before include "Dance music" , "it was launched in Brazil" , "Dance, originally from Brazil" , "Lively ballroom dance from Brazil" , "This ambassador's > brisk steps" .)