Hollows, lairs occupied by termites primarily (5)
I believe the answer is:
dents
'hollows' is the definition.
(I've seen this in another clue)
'lairs occupied by termites primarily' is the wordplay.
'lairs' becomes 'dens' ('den' can be a synonym of 'lair').
'occupied by' indicates putting letters inside.
'primarily' indicates taking the first letters.
The initial letter of 'termites' is 't'.
'dens' placed around 't' is 'DENTS'.
(Other definitions for dents that I've seen before include "Tends towards small depression" , "Tends towards small depressions" , "reductions in size" , "Tends to create small depressions" .)