Unremunerative amateur match (3-6)
I believe the answer is:
non-profit
'unremunerative' is the definition.
(not remunerating someone or providing profit)
'amateur match' is the wordplay.
'amateur' becomes 'non-pro' (non-professional).
'match' becomes 'fit' (synonyms).
'nonpro'+'fit'='NON-PROFIT'
(Other definitions for non-profit that I've seen before include "Uncommercial" , "characterising a charity?" .)