Weapon head of teaching found in new toilets (8)
I believe the answer is:
stiletto
'weapon' is the definition.
(stiletto is a kind of weapon)
'head of teaching found in new toilets' is the wordplay.
'head of' says to take the initial letters.
'found in' is an insertion indicator.
'new' indicates anagramming the letters.
The first letter of 'teaching' is 't'.
'toilets' with letters rearranged gives 'stileto'.
't' placed within 'stileto' is 'STILETTO'.
(Other definitions for stiletto that I've seen before include "Item of footwear" , "Tapering dagger" , "Long dagger" , "Dagger; tapered heel" , "One may have a stab" .)