Just one tango in vest (7)
I believe the answer is:
singlet
'vest' is the definition.
(I know that vest can be written as singlet)
'just one tango' is the wordplay.
I cannot really see how this works, but
'one' could be 'single' (similar in meaning) and 'single' is located in the answer.
'tango' could be 't' (phonetic alphabet: alpha, bravo, charlie etc.) and 't' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for singlet that I've seen before include "One unaccompanied" , "garment worn by men" , "Underwear" , "Something to wear" , "Sleeveless vest" .)