Concentrated in past, present or future? (7)
I believe the answer is:
intense
'concentrated' is the definition.
(similar in meaning)
'in past present or future?' is the wordplay.
'past present or future?' becomes 'tense' (I've seen this in another clue).
'in'+'tense'='INTENSE'
(Other definitions for intense that I've seen before include "Extreme - strong" , "Acute, concentrated" , "Feverish" , "Vived, extreme, acute" , "In an extreme degree" .)