Catches 150 snakes (6)
I believe the answer is:
clasps
'catches' is the definition.
(clasp can mean to clutch or catch)
'150 snakes' is the wordplay.
'150' becomes 'CL' (Roman numerals).
'snakes' becomes 'asps' (asp is a kind of snake).
'cl'+'asps'='CLASPS'
(Other definitions for clasps that I've seen before include "Holds tightly" , "Holds or embraces closely" , "Fasteners, as on necklaces perhaps" , "Necklace fasteners" , "Embraces, hugs" .)