Dancing polka will lead to terribly intimate conversation (6,4)
I believe the answer is:
pillow talk
'intimate conversation' is the definition.
'dancing polka will lead to terribly' is the wordplay.
'dancing' indicates an anagram.
'lead to' indicates taking the first letters.
The initial letter of 'terribly' is 't'.
'polka'+'will'+'t'='polkawillt'
'polkawillt' with letters rearranged gives 'PILLOW TALK'.
(Other definitions for pillow talk that I've seen before include "Conversation in bed" , "romantic comedy film" , "Bedtime conversation" , "Conversations in bed" .)