1) Ages follower 2) Agone 3) An attempt 4) Ancient history adjective 5) At one point 6) At some point in the past 7) Back 8) Back from here 9) Back from now 10) Back in history 11) Back in the day 12) Back in the good old days 13) Back in the olden days 14) Back in the past 15) Back in time 16) Back then Found on https://www.crosswordclues.com/clue/ago
A·go' adjective & adverb [ Middle English ago , agon , past participle of agon to go away, pass by, Anglo-Saxon āgān to pass away; ā- (cf. Goth. us- , German er- , orig. meaning out ) + gān to go. See ... Found on http://www.encyclo.co.uk/webster/A/45