150 always bright (6)
I believe the answer is:
clever
'bright' is the definition.
(bright can mean clever or intelligent)
'150 always' is the wordplay.
'150' becomes 'CL' (Roman numerals).
'always' becomes 'ever' (synonyms).
'cl'+'ever'='CLEVER'
(Other definitions for clever that I've seen before include "Knowledgeable" , "Sharp and able" , "Quick at learning and understanding" , "Smar and canny" , "Quick to learn and understand" .)