Shows testicles at the front: small trunks (3,6)
I believe the answer is:
tea chests
'trunks' is the definition.
(trunks for tea)
'shows testicles at the front small' is the wordplay.
'shows' becomes 'teaches' (shows someone how to do something).
'at the front' suggests taking the first letters.
'small' becomes 's' (abbreviation - e.g. clothes size).
The first letter of 'testicles' is 't'.
'teaches'+'t'+'s'='TEA-CHESTS'
(Other definitions for tea chests that I've seen before include "cargo from India?" , "shipping containers" .)