Learned to be rude about tie design (7)
I believe the answer is:
erudite
'learned' is the definition.
(erudite means learned or well-read)
'rude about tie design' is the wordplay.
'about' indicates anagramming the letters.
'design' indicates anagramming the letters.
'rude' with letters rearranged gives 'erud'.
'tie' anagrammed gives 'ite'.
'erud'+'ite'='ERUDITE'
'to be' acts as a link.
(Other definitions for erudite that I've seen before include "'Learned, knowledgeable (7)'" , "Learned, well educated" , "Learned and scholarly" , "Having or showing great knowledge or learning" , "Full of knowledge" .)