Product of Gilbert, heading off with it (8)
I believe the answer is:
libretti
'product of gilbert heading off with it' is the definition.
I can't judge whether this definition defines the answer.
'of gilbert heading off with it' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'heading off' means to remove the first letter.
'with' means one lot of letters go next to another.
'gilbert' with its first letter taken off is 'ilbert'.
'ilbert' put after 'it' is 'itilbert'.
'itilbert' with letters rearranged gives 'LIBRETTI'.
Can you help me to learn more?
(Other definitions for libretti that I've seen before include "score-books?" , "Words" , "Books" , "Da Ponte's texts" , "Opera texts" .)