Male singer holds quaver (7)
I believe the answer is:
tremble
'quaver' is the definition.
(thesaurus)
'male singer holds' is the wordplay.
'male' becomes 'm' (common abbreviation).
'singer' becomes 'treble' (I've seen this before**).
'holds' means one lot of letters goes inside another.
'm' going within 'treble' is 'TREMBLE'.
(Other definitions for tremble that I've seen before include "quail" , "Shake - quiver" , "Betray nerves" , "Show fear" , "Shiver, quake" .)