V-shape essentially gets thinner top? (7)
I believe the answer is:
against
'v' is the definition.
(v means versus in sports fixtures)
'shape essentially gets thinner top?' is the wordplay.
'essentially' indicates the central letters.
'gets' becomes 'gains' (gaining is a kind of getting).
'top?' indicates taking the first letters (I've seen 'top of' mean this).
The middle of 'shape' is 'a'.
The first letter of 'thinner' is 't'.
'a'+'gains'+'t'='AGAINST'
(Other definitions for against that I've seen before include "In opposition to" , "Opposite to" , "Anti, touching" , "Versus - in contact with" , "Not favouring" .)