College tutor lacking heart (4)
I believe the answer is:
tech
'college' is the definition.
(I've seen this before)
'tutor lacking heart' is the wordplay.
'tutor' becomes 'teach' (I've seen this before).
'lacking heart' means to remove the middle letters.
'teach' with its middle taken out is 'TECH'.
(Other definitions for tech that I've seen before include "College teaching practical skills (informal)" , "The practical use of science, in short" , "Kind of college" , "Abbrev. for a college" .)