Sound made in Alps, intermittently, by loud bell (5)
I believe the answer is:
yodel
'sound made in alps' is the definition.
(yodelling is traditional in Alpine regions)
'intermittently by loud bell' is the wordplay.
'intermittently' indicates alternate letters.
'by'+'loud'+'bell'='byloudbell'
The alternate letters of 'byloudbell' are 'YODEL'.
(Other definitions for yodel that I've seen before include "Sing in Tyrolean fashion" , "Alpine warble" , "Warbling voice" , "Vocalise" , "Sing warblingly" .)