In the teens, being on the move is great (7)
I believe the answer is:
intense
'great' is the definition.
(I've seen this before)
'in the teens being on the move' is the wordplay.
'being on the move' indicates an anagram.
'teens' with letters rearranged gives 'tense'.
'in'+'tense'='INTENSE'
'is' acts as a link.
(Other definitions for intense that I've seen before include "say, description of campers?" , "Deeply felt or vehement" , "amplified?" , "Acute, concentrated" , "In an extreme degree" .)