Look wise in speech about key allegiance (7)
I believe the answer is:
loyalty
'allegiance' is the definition.
(I've seen this before)
'look wise in speech about key' is the wordplay.
I cannot quite understand how this works, but
'look' could be 'lo' ('lo' is an archaic exclamation meaning 'look!') and 'lo' is located in the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
This explanation may well be incorrect...
(Other definitions for loyalty that I've seen before include "Allegiance, commitment" , "Fidelity, allegiance" , "Alligiance and fidelity" , "Firm allegiance" , "Dedication" .)