Peter out with pram initially as diaper exploded (9)
I believe the answer is:
disappear
'peter out' is the definition.
(thesaurus)
'pram initially as diaper exploded' is the wordplay.
'initially' indicates taking the first letters.
'exploded' indicates an anagram.
The initial letter of 'pram' is 'p'.
'p'+'as'+'diaper'='pasdiaper'
'pasdiaper' with letters rearranged gives 'DISAPPEAR'.
'with' acts as a link.
(Other definitions for disappear that I've seen before include "Become invisible" , "go by the board" , "exit" , "Vanish, cease to be visible" , "Fade out" .)