Lack expression to be obvious (2,7,6)
I believe the answer is:
go without saying
'obvious' is the definition.
Both the definition and answer are adjectives.
Perhaps they are linked in a way I don't understand?
'lack expression to' is the wordplay.
I cannot quite see how this works, but
'lack' could be 'gowithout' (I've seen this before) and 'gowithout' is found within the answer.
'expression' could be 'saying' (synonyms) and 'saying' is found in the answer.
No letters remain.
This explanation may well be incorrect...
'be' is the link.
Can you help me to learn more?
(Other definitions for go without saying that I've seen before include "but appear obvious" , "fail to utter on leaving" , "Convey obvious message" , "clear" , "leave Maxim behind" .)