It may follow a slash film, reviewed by one footloose type (7)
I believe the answer is:
divisor
'it may follow a slash' is the definition.
The definition suggests a singular noun which matches the answer.
'film reviewed by one footloose type' is the wordplay.
'film' becomes 'vid' (short for video).
'reviewed' is a reversal indicator.
'by one' becomes 'i' (Roman numeral. I am not sure about the 'by' bit.).
'footloose' means to remove the last letter (the bottom letter or 'foot' is loosened).
'type' becomes 'sort' (I've seen this in another clue).
'vid' reversed gives 'div'.
'sort' with its final letter taken away is 'sor'.
'div'+'i'+'sor'='DIVISOR'
Can you help me to learn more?
(Other definitions for divisor that I've seen before include "Number under line" , "factor" , "B in A/B" , "Sort of number" , "It will go in exactly" .)