Indecent call is a bloomer (8)
I believe the answer is:
bluebell
'a bloomer' is the definition.
(bluebell is a kind of flowering plant)
'indecent call' is the wordplay.
'indecent' becomes 'blue' (I've seen this before).
'call' becomes 'bell' (bell can mean a phone call).
'blue'+'bell'='BLUEBELL'
'is' is the link.
(Other definitions for bluebell that I've seen before include "Plant with bell-shaped flowers" , "Wildflower" , "former dancing girl" , "Pretty flower with azure chime?" , "Common spring-flowering woodland plant" .)