Note about first of Colts, a shooter (7)
I believe the answer is:
minicam
'shooter' is the definition.
(something that shoots film)
'note about first of colts a' is the wordplay.
'note' becomes 'minim' (type of musical note).
'about' means one lot of letters goes inside another.
'first of' indicates taking the first letters.
The first letter of 'colts' is 'c'.
'c'+'a'='ca'
'minim' enclosing 'ca' is 'MINICAM'.
(Other definitions for minicam that I've seen before include "Hand-held device for taking moving images" , "Film maker" .)