Player on bench that's got diminished is farmed out elsewhere (13)

'farmed out elsewhere' is the definition.

'player on bench that's got diminished' is the wordplay.
'player on bench' becomes 'sub' (substitute in football, for example).
'that's got' means one lot of letters go next to another.
'diminished' becomes 'contracted' (contracting is a kind of diminishing).
'sub'+'contracted'='SUBCONTRACTED'

'is' acts as a link.