Tense tailor nervously eating large pancake (8)
I believe the answer is:
tortilla
'pancake' is the definition.
(I know that tortilla is a type of pancake)
'tense tailor nervously eating large' is the wordplay.
'tense' becomes 't' (abbreviation used in many dictionaries).
'nervously' indicates an anagram.
'eating' is an insertion indicator.
'large' becomes 'L' (eg in clothes sizes).
't'+'tailor'='ttailor'
'ttailor' is an anagram of 'tortila'.
'tortila' enclosing 'l' is 'TORTILLA'.
(Other definitions for tortilla that I've seen before include "Cake including maize" , "Mexican snack" , "Mexican 7 across" , "Mexican flatbread" , "Thin unleavened pancake" .)