Fit rugby player has little hesitation (6)
I believe the answer is:
proper
'fit' is the definition.
(thesaurus)
'rugby player has little hesitation' is the wordplay.
'rugby player' becomes 'prop' (I've seen this in other clues).
'has' means one lot of letters go next to another.
'little hesitation' becomes 'er'.
'prop'+'er'='PROPER'
(Other definitions for proper that I've seen before include "Genuine; respectable" , "Refined" , "Genuine; suitable" , "Correct, decent" , "Befitting" .)