Wise to head north in a great lake? (5)
I believe the answer is:
ernie
'wise' is the definition.
(comedian Ernie Wise)
'head north in a great lake?' is the wordplay.
'head' indicates taking the first letters.
'in' indicates putting letters inside.
'a great lake?' becomes 'Erie' (Erie is one of the Great Lakes).
The initial letter of 'north' is 'n'.
'n' placed into 'erie' is 'ERNIE'.
'to' is the link.
(Other definitions for ernie that I've seen before include "Premium Bond picker" , "Man - chooses Premium Bond winners" , "Bondsman" , "Boy" , "___ Wise, d. 1999" .)