Romantic big day oddly ignored by lecturer Alice essentially (7)
I believe the answer is:
idyllic
'romantic' is the definition.
(thesaurus)
'big day oddly ignored by lecturer alice essentially' is the wordplay.
'oddly ignored' indicates alternate letters.
'by' means one lot of letters go next to another.
'lecturer' becomes 'l'.
'essentially' indicates the central letters.
The middle letters of 'alice' are 'lic'.
'big'+'day'='bigday'
The alternating letters of 'bigday' are 'idy'.
'idy'+'l'+'lic'='IDYLLIC'
(Other definitions for idyllic that I've seen before include "Unspoiled and perfect" , "Charming, picturesque" , "Perfectly delightful" , "Blissfully peaceful" , "Arcadian, peaceful" .)