Unable to think clearly, that chap in Dirty Dancing (7)
I believe the answer is:
dithery
'unable to think clearly' is the definition.
(dithering or wavering about a decision)
'chap in dirty dancing' is the wordplay.
'chap' becomes 'he'.
'in' means one lot of letters goes inside another.
'dancing' indicates an anagram.
'dirty' anagrammed gives 'ditry'.
'he' inserted inside 'ditry' is 'DITHERY'.
'that' is the link.
(Other definitions for dithery that I've seen before include "Hesitating" , "Hesitant" , "Indecisive" , "Unsure" , "shaking" .)