Concentrate - caught on boundary (8)
I believe the answer is:
converge
'concentrate' is the definition.
(I know that concentrate is a more specific form of converge)
'caught on boundary' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'boundary' becomes 'verge' (verge is a kind of boundary).
'c'+'on'+'verge'='CONVERGE'
(Other definitions for converge that I've seen before include "Approach a single point" , "Move towards meeting" , "Come together" , "Tend towards a common point" , "Come towards the same point like Congreve" .)