Alexander's father spoke with encouragement (6)
I believe the answer is:
fillip
'encouragement' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for fillip that I've seen before include "Encouraging boost" , "As tonic" , "Stimulus or incentive" , "Something adding stimulation" , "19, which sounds like a boy's name" .)