Short satirical piece concerning small equipment (4)
I believe the answer is:
skit
'short satirical piece' is the definition.
(I've seen this before)
'small equipment' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'equipment' becomes 'kit' (kit is a kind of equipment).
's'+'kit'='SKIT'
'concerning' acts as a link.
(Other definitions for skit that I've seen before include "Brief satirical sketch" , "Short play which makes fun of something" , "Short comic piece" , "A piece of humorous mimicry" , "piece of satire" .)