Dope one I love gets in Delft on vacation (5)
I believe the answer is:
idiot
'dope' is the definition.
(I've seen this before)
'one i love gets in delft on vacation' is the wordplay.
'one' becomes 'i' (Roman numeral).
'love' becomes 'o' (In tennis, 'love' means 'zero').
'gets in' is an insertion indicator.
'on vacation' suggests removing the centre.
'delft' with its middle removed is 'dt'.
'i'+'o'='io'
'io' inserted within 'dt' is 'diot'.
'i'+'diot'='IDIOT'
(Other definitions for idiot that I've seen before include "Silly ass" , "Dostoevsky hero" , "Unwise person" , "Fool, silly person" , "Dope" .)