Twirl in tango with violin, losing head (7)
I believe the answer is:
twiddle
'twirl' is the definition.
('twiddle' can be a synonym of 'twirl')
'tango with violin losing head' is the wordplay.
'tango' becomes 't' (phonetic alphabet: alpha, bravo, charlie etc.).
'with' becomes 'w' (abbreviation).
'violin' becomes 'fiddle' ('fiddle' can be a synonym of 'violin').
'losing head' means to remove the first letter.
'fiddle' with its initial letter taken away is 'iddle'.
't'+'w'+'iddle'='TWIDDLE'
'in' is the link.
(Other definitions for twiddle that I've seen before include "Play nervously (with something)" , "Twirl (thumbs?)" , "Finger idly" , "Idly rotate (one's thumbs?)" , "Jiggle" .)