To add to stevesmi's point — Clenbuterol is a beta-2 agonist and thermogenic, it has no interaction with the hypothalamic-pituitary-gonadal axis and does nothing to restore natural testosterone production. People confuse it as a PCT product because it's sometimes used during "cutting" phases around PCT timing, but functionally it's irrelevant to recovery of the HPTA.
Proper PCT after Anavar (even though Anavar is relatively mild on suppression vs. injectable steroids):
Nolvadex (Tamoxifen) 20mg/day for 4 weeks or Clomid 50/50/25/25 protocol are the standard SERM options. Enclomiphene is becoming more popular as a cleaner alternative to Clomid without the mixed agonist/antagonist effects.
Supporting the PCT with MK-677 (Ibutamoren) is a common stack since MK-677 doesn't suppress the HPTA and can help with the muscle/strength preservation during the hormonal transition back to baseline. It also supports sleep quality which is when testosterone pulses occur.
Bloodwork 4-6 weeks after PCT completion tells you definitively where you landed. This is non-optional if you're going to continue cycling.