Commonly, money (apart from euro) is thin (7)
I believe the answer is:
thready
'is thin' is the definition.
(similar in meaning)
'commonly money' is the wordplay.
'commonly' becomes 'th' (I can't justify this - if you can you should give a lot more credence to this answer).
'money' becomes 'ready' (I've seen this before).
'th'+'ready'='THREADY'
'apart from euro' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
(Other definitions for thready that I've seen before include "Like some yarn" , "Like some yarns" .)