Relish being on top initially in pub game (7)
I believe the answer is:
botargo
'relish' is the definition.
(I have seen 'Fishy relish' mean 'botargo' so perhaps 'relish' could also mean 'botargo')
'on top initially in pub game' is the wordplay.
'initially' indicates taking the first letters.
'in' indicates putting letters inside.
'pub' becomes 'bar' (I've seen this before).
'game' becomes 'go' (go game is a kind of game**).
The first letters of 'on top' is 'ot'.
'ot' put within 'bar' is 'botar'.
'botar'+'go'='BOTARGO'
'being' acts as a link.
(Other definitions for botargo that I've seen before include "Fishy relish" , "pressed roe" , "Fish rolls" .)