Before first kiss, nervously phone fabulous bird (7)
I believe the answer is:
phoenix
'fabulous bird' is the definition.
(mythical or fabulous bird)
'before first kiss nervously phone' is the wordplay.
'before' says to put letters next to each other.
'first' becomes 'i' (I in Roman numerals eg Elizabeth I).
'kiss' becomes 'x' (X can represent a kiss).
'nervously' is an anagram indicator.
'phone' with letters rearranged gives 'phoen'.
'i'+'x'='ix'
'ix' put after 'phoen' is 'PHOENIX'.
(Other definitions for phoenix that I've seen before include "Mythological bird" , "Mythical bird rising from funeral pyre" , "Reborn bird" , "part of Arizona" , "Legendary bird -- Arizona city" .)