A fellow also turns up (5)
I believe the answer is:
afoot
'up' is the definition.
(as in 'something's up' and 'something's afoot')
'a fellow also turns' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'also' becomes 'too' ('too' can be a synonym of 'also').
'turns' says the letters should be written in reverse.
'too' back-to-front is 'oot'.
'a'+'f'+'oot'='AFOOT'
(Other definitions for afoot that I've seen before include "Going on" , "in the air" , "Under way (like hunted game?)" , "In the wind" , "Currently in progress" .)