Force the centre of basic lock (6)
I believe the answer is:
stress
'force' is the definition.
(stress is a kind of force)
'the centre of basic lock' is the wordplay.
'the centre of' says to take the centre.
'lock' becomes 'tress' (I've seen this before).
The middle of 'basic' is 's'.
's'+'tress'='STRESS'
(Other definitions for stress that I've seen before include "Ictus" , "Emotional tension" , "result of being overworked" , "Particular emphasis" , "Emphasise the pressure" .)