Worried, tiptoe in to ask (8)
I believe the answer is:
petition
'ask' is the definition.
(thesaurus)
'worried tiptoe in' is the wordplay.
'worried' indicates an anagram.
'tiptoe'+'in'='tiptoein'
'tiptoein' anagrammed gives 'PETITION'.
'to' acts as a link.
(Other definitions for petition that I've seen before include "Written request" , "Formal request submitted to authority" , "Entreaty" , "Prayer" , "Suit - supplication" .)