Cut tin and aluminium (5)
I believe the answer is:
canal
'cut' is the definition.
(thesaurus)
'tin and aluminium' is the wordplay.
'tin' becomes 'can' (synonyms).
'and' means one lot of letters go next to another.
'aluminium' becomes 'al' (Al is the chemical symbol for aluminium).
'can'+'al'='CANAL'
(Other definitions for canal that I've seen before include "Artificial waterway as at Panama (5)" , "Grand Union perhaps" , "Man-made channel of water" , "Manmade flower" , "eg Grand Union" .)