Being there could produce a decent tan! (10)
I believe the answer is:
attendance
'being there' is the definition.
(to attend something is to be at it)
'produce a decent tan' is the wordplay.
'produce' indicates anagramming the letters (I've seen 'producing' mean this).
'a'+'decent'+'tan'='adecenttan'
'adecenttan' anagrammed gives 'ATTENDANCE'.
'could' acts as a link.
(Other definitions for attendance that I've seen before include "all that turned up" , "Service" , "Presence; gate" , "Turnout" , "how many are watching?" .)