Remove energy beam, catching cold (9)
I believe the answer is:
eradicate
'remove' is the definition.
(thesaurus)
'energy beam catching cold' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mca).
'beam' becomes 'radiate' ('radiate' can be a synonym of 'beam'**).
'catching' means one lot of letters goes inside another.
'cold' becomes 'c' (eg on taps).
'radiate' going around 'c' is 'radicate'.
'e'+'radicate'='ERADICATE'
(Other definitions for eradicate that I've seen before include "Root out" , "Destroy completely" , "carry out a purge" , "Scotch" , "Kill" .)