Model-making without a ruler enlists firm friends, maybe (6)
I believe the answer is:
sitcom
'without a ruler enlists firm friends maybe' is the definition.
I can't tell whether this defines the answer.
'model-making' is the wordplay.
'model' becomes 'sit' (e.g. for a painting).
'making' becomes 'com' (I can't justify this - if you can you should give a lot more credence to this answer).
'sit'+'com'='SITCOM'
Can you help me to learn more?
(Other definitions for sitcom that I've seen before include "Friends, for example" , "TV series (colloq.)" , "Humorous serial show" , "Friends perhaps" , "Form of TV comedy" .)