A dry iron — sadly commonplace (8)
I believe the answer is:
ordinary
'commonplace' is the definition.
('ordinary' can be similar in meaning to 'commonplace')
'a dry iron sadly' is the wordplay.
'sadly' indicates an anagram.
'a'+'dry'+'iron'='adryiron'
'adryiron' anagrammed gives 'ORDINARY'.
(Other definitions for ordinary that I've seen before include "Plain" , "Customary" , "Typical" , "'Usual, everyday (8)'" , "standard" .)