Colleague to level with head teacher, no hesitation (7)
I believe the answer is:
partner
'colleague' is the definition.
(I've seen this before)
'level with head teacher no hesitation' is the wordplay.
'level' becomes 'par' (average level on a golf course).
'with head' suggests taking the first letters (I've seen 'with head of' mean this).
'hesitation' becomes 'er' (sound made while hesitating - um, er).
The first letters of 'teacher no' is 'tn'.
'par'+'tn'+'er'='PARTNER'
'to' is the link.
(Other definitions for partner that I've seen before include "Dancing companion" , "Significant other" , "Comrade" , "Professional colleague" , "Consort" .)