Cricketers in a game bagging a couple of fifties (3-8)

'cricketers' is the definition.
(I know this)

'a game bagging a couple of fifties' is the wordplay.
'game' becomes 'rounders' (rounders is a kind of game).
'bagging' means one lot of letters goes inside another (bag can mean to take or obtain).
'a couple of fifties' becomes 'LL' (L is the Roman numeral for fifty).
'a'+'rounders'='arounders'
'arounders' placed around 'll' is 'ALL-ROUNDERS'.

'in' acts as a link.