Need a platform - supported by one Conservative associate ineffectually (15)

'ineffectually' is the definition.
Both the definition and answer are adverbs. Maybe they are linked in a way I don't understand?

'need a platform supported by one conservative associate' is the wordplay.
I cannot really understand how this works, but
'need' could be 'lack' (to lack something is to be in need of it) and 'lack' is present in the answer.
'a' is within the answer.
'platform' could be 'dais' (dais is a kind of platform) and 'dais' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
'conservative' could be 'c' (UK political abbreviation) and 'c' is located in the answer.
'associate' could be 'ally' (ally is a kind of associate) and 'ally' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...

Can you help me to learn more?