Great in the old days: you lit pipe inside (6)
I believe the answer is:
yippee
'great in the old days' is the definition.
I can't judge whether this defines the answer.
'you lit pipe inside' is the wordplay.
'you' becomes 'ye' (historical version of 'you').
'lit' indicates an anagram (lit can mean drunk).
'inside' is an insertion indicator.
'pipe' is an anagram of 'ippe'.
'ye' placed around 'ippe' is 'YIPPEE'.
Can you help me to learn more?
(Other definitions for yippee that I've seen before include "Cry of wild delight" , "Cry of excitement" , "I'm very very very pleased!" , "Excellent!" , "Exclamation of wild delight (colloq.)" .)