Adequate nurse has cold symptom, but no cold (6)
I believe the answer is:
enough
'adequate' is the definition.
(I know that adequate can be written as enough)
'nurse has cold symptom but no cold' is the wordplay.
'nurse' becomes 'EN' (abbreviation for enrolled nurse).
'has' means one lot of letters go next to another.
'cold symptom' becomes 'cough' (I've seen this before).
'but no' suggests deleting specific letters.
'cold' becomes 'C' (abbreviation, eg on taps).
'cough' with 'c' taken away is 'ough'.
'en'+'ough'='ENOUGH'
(Other definitions for enough that I've seen before include "Ample, sufficient" , "As much as required" , "This is going no further!" , "It's said to be as good as a feast" , "As much as necessary" .)