Temporary Head of IT coming on board during semester (7)
I believe the answer is:
interim
'temporary' is the definition.
(similar in meaning)
'head of it coming on board during semester' is the wordplay.
'head of' suggests taking the first letters.
'coming on board' means one lot of letters goes inside another.
'during' becomes 'in' (e.g. during February means in February).
'semester' becomes 'term' (I've seen this before).
The first letter of 'it' is 'i'.
'in'+'term'='interm'
'i' inserted inside 'interm' is 'INTERIM'.
(Other definitions for interim that I've seen before include "An intervening period of time" , "temporary period" , "Meantime - provisional" , "acting" , "Meantime; temporary" .)