Prevalent around glen (4)
I believe the answer is:
vale
'glen' is the definition.
(I've seen this in other clues)
'prevalent around' is the wordplay.
'around' indicates the answer is hidden within the clue.
'VALE' is hidden in the letters of 'prevalent'.
(Other definitions for vale that I've seen before include "'''Sweet ... of Avoca, how calm could I rest'' (Moore) (4)'" , "Maida -, N. London area; farewell (archaic)" , "Long depression containing a river" , "Cheers" , "Valley" .)