Monica and I dancing in promotion for body-builder (5,4)
I believe the answer is:
amino acid
'body-builder' is the definition.
I can't judge whether this defines the answer.
'monica and i dancing in promotion' is the wordplay.
'and' says to put letters next to each other.
'dancing' indicates anagramming the letters.
'in' is an insertion indicator.
'promotion' becomes 'ad' (short for advert).
'monica' after 'i' is 'imonica'.
'imonica' is an anagram of 'minoaci'.
'minoaci' inserted inside 'ad' is 'AMINO-ACID'.
'for' is the link.
Can you help me to learn more?
(Other definitions for amino acid that I've seen before include "Chemical" , "compound for life" , "Organic compound in proteins" , "source of protein required?" , "Basic protein constituent" .)